Peel potatoes or leave skins on, and cut into 1/2-inch chunks. Chop off the broccoli stems if using fresh, and roughly chop the broccoli into small chunks. Boil potatoes and broccoli together for 20 minutes, stirring occasionally.

Drain the potatoes and broccoli into a colander or sieve, then return them to the pot and add the butter, cream, salt, pepper and garlic powder. Use an electric mixer or potato masher, blend the ingredients until smooth.